Found this thread and I thought would try and see if it help.
My account has been un accessible since around 6.30 last night .
I'm expecting a couple of urgent emails so need access asap
Your mailbox is not available at the moment.
Please retry again in one hour and make sure you are using the correct password to access your email from all of your devices.
If the problem continues, please call our team for help on 150 from a Virgin Media phone or mobile, or 0345 454 1111 from any other phone and select option 2. For details about how much it costs to call our team from a Virgin Media home phone, visit virginmedia.com/callcosts. Call costs from other networks and mobiles vary.
Hi Peter, sorry to hear of this. Did you follow the instructions in this thread posted by @Graham_A?
Let us know if you are still having access issues following completing the troubleshooting steps. Also please be aware our working hours are slightly different due to the New Years bank holidays, but we will get back to supporting you as soon as we can.